This application claims the benefit of Japanese Application No. Hei. 10-152924 filed Jun. 2, 1998, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an auxiliary acceleration sensor device for use with an air bag system which is installed in a vehicle such that when the vehicle collides with another, an air bag inflates to protect a driver against any large impact.
2. Discussion of the Related Art
At the time of vehicle collision, a large impact is applied to a vehicle, and a large acceleration is generated in the vehicle. An air bag system installed on the vehicle senses the acceleration by an acceleration sensor and sends an output signal to an inflator, which in turn inflates an air bag. The acceleration sensor for sensing an acceleration of the vehicle is generally located at the central part of the vehicle body. This type of sensor is disclosed in Japanese Utility Model Examined Publication Hei. 8-5077 and Japanese Utility Model Unexamined Publication Hei. 5-23141, for example.
In designing an air bag, which is installed in a steering wheel to protect a driver against the collision impact, the air bag system is designed to operate only when the vehicle receives an impact in the longitudinal direction. The system is inhibited from operating in response to impacts applied in the right and left directions and the back-to-front direction. Thus, additional systems have been proposed to use an auxiliary acceleration sensor that will specify the direction of an impact applied to the vehicle.
A mechanical sensor is used for the auxiliary acceleration sensor of this type. However, the mechanical sensor has a number of disadvantages. For example, the mechanical sensor""s response rate is low, and it is likely to mistakenly operate in response to an obliquely applied impact. With the use of the mechanical sensor, the air bag system cannot flexibly control the air bag operation and is not adaptable for various types of vehicle collisions.
Accordingly, an object of the present invention is to provide an auxiliary acceleration sensor device in use with an air bag system, which succeeds in solving the above problems.
An object of the present invention is to improve response rate and impact detection precision of an auxiliary acceleration sensor device for an air bag system.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, in one aspect of the present invention there is provided an air bag system comprising a main controller that controls operation of an air bag; a main acceleration sensor that senses an acceleration of a vehicle carrying the air bag system; and an auxiliary acceleration sensor device, located at a periphery of the vehicle, that senses an acceleration of the periphery of the vehicle, the auxiliary acceleration sensor device comprising a longitudinal sensor that senses a longitudinal acceleration of the vehicle and generates a longitudinal acceleration signal; a lateral sensor that senses a lateral acceleration of the vehicle and generates a lateral acceleration signal; a first set of comparators that compare the longitudinal acceleration signal with each of a first preselected set of acceleration values and generate a first set of comparator output signals, each of the first set of comparator output signals corresponding to one of the first preselected set of acceleration values; a second set of comparators that compare the lateral acceleration signal with each of a second set of preselected values of acceleration and generate a second set of comparator output signals, each of the second set of comparator output signals corresponding to one of the second preselected set of acceleration values, the first and second set of preselected acceleration values being related by an acceleration discriminating pattern comprising a plurality of areas stepwise arranged, each of the areas being defined by the first and second set of preselected acceleration values; AND elements, each having an AND element output signal, the AND elements logically multiplying each output signal of the first set of comparator output signals with a related output signal of the second set of comparator output signals; and an OR circuit that logically sums the AND element output signals and outputs a result to the main controller.
In another aspect of the present invention, there is provided an air bag system comprising a main controller for controlling an operation of an air bag; a main acceleration sensor for sensing an acceleration of a vehicle carrying the air bag system; and an auxiliary acceleration sensor device, located at a periphery of the vehicle, for sensing an acceleration of the periphery of the vehicle, the auxiliary acceleration sensor device comprising a plurality of series circuits connected in parallel, each series circuit comprising a longitudinal switch being turned on when a detected acceleration reaches a first preselected value defined by one area of an acceleration discriminating pattern; and a lateral switch being turned off when a detected acceleration reaches a second preselected acceleration value defined by one of the areas of the acceleration discriminating pattern, and the acceleration discriminating pattern is defined by related sets of lateral and front-to-rear acceleration values.
In yet another aspect of the present invention, there is provided an air bag system, comprising a main controller for controlling the operation of the air bag; a main acceleration sensor device for sensing an acceleration of a vehicle carrying the air bag system; and an auxiliary acceleration sensor, located at a periphery of the vehicle, for sensing an acceleration of the periphery of the vehicle, the auxiliary sensor device comprising longitudinal sensor means for sensing a longitudinal acceleration of the vehicle, the longitudinal sensor means having an output; lateral sensor means for sensing a lateral acceleration of the vehicle, the lateral sensor means having an output; first and second comparator means each having output signals and operating on the basis of an acceleration discriminating pattern comprising a plurality of areas stepwise arranged, each of the areas being defined by related levels of output signals of the longitudinal sensor means and the lateral sensor means, the first comparator means for determining if a sensed longitudinal acceleration is larger than a predetermined value of acceleration in each area of the acceleration discriminating pattern, the second comparator means for determining if a sensed lateral acceleration is smaller than a predetermined value of acceleration in each area of the acceleration discriminating pattern; an AND circuit, having output signals and comprising a plurality of AND elements, for logically multiplying the output signals of the first comparator means and the second comparator means; and an OR circuit for logically summing the output signals of the AND elements of the AND circuit and outputting a result to the main controller.
In still another aspect of the present invention, there is provided an air bag system comprising a main controller for controlling an operation of an air bag; a main acceleration sensor for sensing an acceleration of a vehicle; and an auxiliary acceleration sensor device, located at a periphery of the vehicle, for sensing an acceleration of the periphery of the vehicle, the auxiliary acceleration sensor device including a plurality of series circuits connected in parallel, each series circuit comprising longitudinal switching means being turned on when a sensed acceleration reaches a first preset acceleration value of each the area of an acceleration discriminating pattern; and lateral switching means being turned off when a sensed acceleration reaches a second preset acceleration value of each the area of the acceleration discriminating pattern.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention.